Fe–Ni–Co Alloy Derived Ternary Disulfide for High‐Performance Thermal Battery

Due to the advantages of excellent thermal stability, high electronic conductivity, and high specific capacity, transition metal disulfides and their composites are the main cathode materials for thermal batteries. However, common methods for the preparation of disulfide composites are confronted with the problem of low production efficiency. Herein, Fe–Ni–Co ternary disulfide (a‐FeNiCoS 2 ) is prepared via a simple high‐temperature thermal sintering process using Fe–Ni–Co alloy as metal source. The present a‐FeNiCoS 2 is composed by heteroatoms doped NiS 2 and FeS 2 , which then form heterostructure. As a result, a‐FeNiCoS 2 delivers low internal resistance, high specific capacity, and wide operating temperature range in thermal batteries. A high specific capacity of 562 mAh g −1 is obtained at the current density of 200 mA cm −2 and discharging temperature of 500 °C with a cutoff voltage of 1.5 V, which still remains at 441 mAh g −1 with a cutoff voltage of 1.6 V. The result indicates that a‐FeNiCoS 2 possesses greatly improved depth of the first discharge plateau, which is beneficial to enhance the energy density of thermal battery. This work provides a facile method for preparing ternary disulfide for high performance thermal batteries.